Use opacity modifier instead of conditionals to hide unselected timelines to retain scroll positions

Changelog-Fixed: Use opacity modifier instead of conditionals to hide unselected timelines to retain scroll positions

damus/ContentView.swift

@@ -153,26 +153,25 @@ struct ContentView: View {
     }
     
     func MainContent(damus: DamusState) -> some View {
-        VStack {
+        ZStack {
-            switch selected_timeline {
-            case .search:
             if #available(iOS 16.0, *) {
                 SearchHomeView(damus_state: damus_state!, model: SearchHomeModel(damus_state: damus_state!))
                     .scrollDismissesKeyboard(.immediately)
+                    .opacity(selected_timeline == .search ? 1 : 0)
             } else {
                 // Fallback on earlier versions
                 SearchHomeView(damus_state: damus_state!, model: SearchHomeModel(damus_state: damus_state!))
+                    .opacity(selected_timeline == .search ? 1 : 0)
             }
 
-            case .home:
             PostingTimelineView
+                .opacity(selected_timeline == .home ? 1 : 0)
 
-            case .notifications:
             NotificationsView(state: damus, notifications: home.notifications)
+                .opacity(selected_timeline == .notifications ? 1 : 0)
 
-            case .dms:
             DirectMessagesView(damus_state: damus_state!, model: damus_state!.dms, settings: damus_state!.settings)
-            }
+                .opacity(selected_timeline == .dms ? 1 : 0)
         }
         .navigationBarTitle(timeline_name(selected_timeline), displayMode: .inline)
         .toolbar {

damus/Views/DirectMessagesView.swift

@@ -18,6 +18,7 @@ struct DirectMessagesView: View {
     @State var dm_type: DMType = .friend
     @ObservedObject var model: DirectMessagesModel
     @ObservedObject var settings: UserSettingsStore
+    @SceneStorage("ContentView.selected_timeline") var selected_timeline: Timeline = .home
 
     func MainContent(requests: Bool) -> some View {
         ScrollView {
@@ -90,6 +91,7 @@ struct DirectMessagesView: View {
             .tabViewStyle(.page(indexDisplayMode: .never))
         }
         .toolbar {
+            if selected_timeline == .dms {
                 ToolbarItem(placement: .navigationBarTrailing) {
                     if would_filter_non_friends_from_dms(contacts: damus_state.contacts, dms: self.model.dms) {
 
@@ -97,6 +99,7 @@ struct DirectMessagesView: View {
                     }
                 }
             }
+        }
         .navigationTitle(NSLocalizedString("DMs", comment: "Navigation title for view of DMs, where DM is an English abbreviation for Direct Message."))
     }
 }

damus/Views/Notifications/NotificationsView.swift

@@ -82,6 +82,7 @@ struct NotificationsView: View {
     @ObservedObject var notifications: NotificationsModel
     @StateObject var filter = NotificationFilter()
     @SceneStorage("NotificationsView.filter_state") var filter_state: NotificationFilterState = .all
+    @SceneStorage("ContentView.selected_timeline") var selected_timeline: Timeline = .home
 
     @Environment(\.colorScheme) var colorScheme